Loren Cordain, Ph.D., retired in December after 32 years as a professor at CSU, where he specialized in nutritional anthropology. He lives in south Fort Collins with his wife and youngest son, and from his home office, he works with his last graduate student at CSU and with a handful of scientists from around the world who have asked him to co-author their publications.

Cordain is still in high demand following his 2002 book “The Paleo Diet,” in which he recommended that modern humans eat like their Paleolithic ancestors, with meat and fish, fresh vegetables, fruit and nuts. That book’s publication spawned a devout following, three more books and a website that attracts 1 million visitors each month. Cordain has already sold more than 500,000 copies of his first four publications, and he is working on another cookbook, set to publish in 2015.

The Coloradoan sat down with Cordain in his Fort Collins home, where he showed us a few of the most recent scientific papers on the topic, as well as his own research … and even the contents of his refrigerator.

In his basement “man cave,” Cordain keeps 25 years of research on his caveman diet, all of it still in paper boxes following retirement. In the corner of the den is a large freezer filled with cuts of bison, deer, elk, blue grouse and pheasant and their organs — liver and tongue. Meat is one of the staples of the paleo diet Cordain writes about and practices at home.

If you were to go back here to Colorado 200 years ago, everybody ate in a similar manner. … They didn’t have cereal grains, they didn’t have any refined sugars, and they had no processed foods. When you think about that, 70 percent of the calories in a typical U.S. diet come from four foods that hunter-gatherers never ate: refined sugars, refined grains, refined vegetable oil and dairy products.

Coloradoan: Essentially, processed foods. But what about legumes?

Cordain: Legumes are not part of (the paleo diet), and the reason for that is because legumes are inedible unless they’re cooked. We simply can’t assimilate the starch, because it has to be broken down … also legumes have considerable toxic components, for instance raw red kidney beans will make you very, very ill.

Coloradoan: How do celiac disease and gluten intolerance play into paleo?

Cordain: Now, we’re looking at a relative epidemic of people who don’t do well with wheat and gluten-containing grains. So why is that? Because we simply as a species have not had sufficient time evolutionarily to adapt to a non-traditional food. … I think it lends support to the idea that we don’t have a (nutritional) wheat requirement. When you look at wheat or any grain and compare it to fresh fruits or vegetables or fish, it comes out almost at the bottom in the 13 vitamins and minerals that are most lacking in the U.S. diet. Why would you want to deliberately eat a food that dilutes the vitamin and mineral content of your diet?

Coloradoan: (Cordain initially read about paleo nutrition in an article published by Dr. Boyd Eaton in the New England Journal of Medicine.) What was so novel about Eaton’s concept?

Cordain: He wrote that in 1985, and I got around to reading it in ’87, and I thought, this is just about the best idea I’ve seen on diet and health. (Before paleo), what we had thought about what was healthy eating came from humans, so “experts” who knew what we should and should not be eating … that’s where the information had always come from. And humans are fallible.

(The paleo) diet is based on our genes, and so the concept that Boyd had brought up is that if you go backward in time, it’s kind of like peeling an onion, you get to a point where everything we eat now and consider normal didn’t exist. And if you can appreciate it on an evolutionary timescale, 10,000 years ago seems to be historically remote, but it’s only about 300 human generations ago. Once you go back 10,000 years, everybody on the planet was a hunter-gatherer and had been for 2.5 million years. Even though my name is associated with it, I didn’t invent this diet. What we did was simply uncover what was pre-existing.

Coloradoan: You didn’t set out to create a diet craze. What did you consider the paleo diet?

Cordain: A lifetime program of healthy eating to reduce your risk of chronic disease.

That’s one reason why it’s gained so much traction, is that it works. I think it’s the 21st-century version of what we now believe to be one of the healthiest ways to eat. Back in the ’70s and ’80s when I was growing up, we thought it was a vegan/vegetarian diet. And I think there will never be agreement on what people should and should not eat … but this is an idea whose time has come, and we now have experimental confirmation.